We first would divide the Pentagon into two shapes, one a square and the other a triangle. To find the height of the triangle we must minus the 15cm to the 10cm, which gives us 5cm.
5cm= height of triangle
7cm= base of triangle
Then, apply the area of triangle formula
which is: A=(b×h)÷2
so the area would be 17.5cm squared.
For the square, 10= height and the 7=base
The formula for rectangles is:
A=b×h
so, the area is 70cm squared.
if you want the total area add the two area together, which equals 87.5cm squared.
I hope this helps.